Bob, I would suggest getting your head unit repaired could prove expensive and not necessarily end the problems. Many here have fitted aftermarket head units and the cost isn't prohibitive but repair might be a blank cheque with doubtful success. It may be worth checking with someone who does electronic repairs as to cost but it appears Toyota has washed its hands of these units and even they have gone to something else.
As to semiconductors etc. Yes many electronic items made in China have been made to the design specifications but using low cost components and the outcome is inevitable. Electronic repairers are often able to replace the inferior component to make the unit better than new but it can be expensive to replace a capacitor worth $2 because the labour needed to find the fault is quite unpredictable. Someone who has intimate knowledge about the problem could fix it but it can be like opening a can of worms, some hobbyists replace components easily but first they must understand what is causing the issue.
Might be worth checking this thread, or finding a 2nd hand one at a wreckers.
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